TWI573844B - Gap-fill methods - Google Patents

Description

Interstitial method

The present invention is generally related to a method of fabricating an electronic device. More particularly, the present invention relates to a gap filling method that can be applied to semiconductor device processes. This method is particularly suitable for filling gaps, such as trenches for device isolation.

In the semiconductor manufacturing industry, a large number of electronic devices are fabricated on semiconductor substrates. As each new design node appears to have a higher integration density, the devices are assembled using increasingly smaller geometric spaces, reducing the space between them. As a result, the aspect ratio is also increased, which brings various process challenges.

One of the challenges is a gap-filling process in which a gap, such as a trench, a hole, or an inter-line space, is filled with material for planarization, isolation, or other purposes. As an example of a gap-filling process, shallow trench isolation (STI) is used to prevent leakage currents between adjacent transistors due to small geometric spaces and spacing between devices. Among them, the STI process is described in, for example, US 5854112A. In this process, the trench structure is formed by imaging the trench pattern prior to the photoresist layer. The photoresist pattern is then transferred to a lower substrate, such as a germanium substrate or other layer on the substrate, typically by anisotropic dry etching. After the trench is dielectric The material is filled, such as ruthenium dioxide, using, for example, chemical vapor deposition (CVD) or spin-on-glass (SOG). Excess dielectric materials are typically removed using chemical mechanical planarization (CMP).

Devices having a geometric space of about 20 nanometers (sub-20 nm), such as grooves, holes, and other slits, generally have a high aspect ratio. This high aspect ratio feature may be difficult to fill with conventional methods without creating a large number of voids. The presence of voids can cause various problems, have an adverse effect on device reliability, and/or cause defects. For example, in an STI process, the formation of holes can result in poor electrical isolation, resulting in leakage currents between adjacent devices. In order to avoid the formation of defects between the devices, it is desirable that the gap to be filled be filled in a void-free manner. However, due to the reduced size and limited by the gap filler material and process conditions, it may be difficult.

There is still a need in the semiconductor manufacturing industry for an improved method for filling gaps including high aspect ratios.

In one aspect of the invention, a method of interstitial is provided. The method comprises: (a) providing a semiconductor substrate having an embossed image on a surface, the embossed image comprising a plurality of slits to be filled; (b) applying the interstitial composition to the embossed image, wherein the interstitial composition comprises a crosslinkable polymer, an acid catalyst, a crosslinking agent, and a solvent which are not crosslinked, wherein the crosslinkable polymer comprises a first unit having the following general formula (I) and a first formula (II) second block: Wherein: R ₁ is selected from hydrogen, fluoro, C ₁ -C ₃ alkyl and C ₁ -C ₃ fluoroalkyl group; and Ar ₁ is an aryl group containing no crosslinkable group of the optionally substituted; Wherein: R _{3 is} selected from the group consisting of hydrogen, fluorine, C ₁ -C ₃ alkyl and C ₁ -C ₃ fluoroalkyl; and R _{4 is} selected from C ₁ to C ₁₂ straight, branched or cyclic as desired. And a C ₆ to C ₁₅ aryl group optionally substituted with a hetero atom, wherein at least one hydrogen atom is substituted with a functional group independently selected from a hydroxyl group, a carboxyl group, a thiol, an amine An epoxy group, an alkoxy group, a decylamine, and a vinyl group; and (c) heating the interstitial composition at a temperature at which the polymer is crosslinked.

The nomenclature used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular forms "a", "the"

2‧‧‧Semiconductor substrate

4‧‧‧Relief imagery

6‧‧‧ gap

8‧‧‧Interstitial composition

8'‧‧‧crosslinked polymer

12, 14‧‧‧ heating plate or oven

16 ‧ ‧ layer

h ‧‧‧height

w ‧‧‧Width

The invention will be described with reference to the following drawings, in which like reference numerals indicate similar features, wherein: FIGS. 1A to 1D illustrate a first interstitial method of the present invention; 2A to 2F illustrate the second interstitial method of the present invention; FIGS. 3A and 3B show SEM photomicrographs of the groove pattern after filling; and FIGS. 4A to 4D show SEM photomicrographs of the groove pattern after filling Figure.

The interstitial method of the present invention involves applying an interstitial composition to a relief image of the surface of the substrate. The interstitial composition includes an uncrosslinked crosslinkable polymer, an acid catalyst, a crosslinking agent, and a solvent, and includes one or more additional optional components.

The uncrosslinked crosslinkable polymer (also referred to herein as a crosslinkable polymer) comprises a first unit of the following general formula (I): Wherein R _{1 is} selected from the group consisting of hydrogen, fluorine, C ₁ -C ₃ alkyl and C ₁ -C ₃ fluoroalkyl, wherein hydrogen is typically; and Ar ₁ is an optionally substituted aryl. Preferably, Ar ₁ comprises 1, 2 or 3 aromatic carbocyclic rings and/or heteroaromatic rings. Preferably, the aryl group contains a single aromatic ring, more preferably a benzene ring. When a plurality of aromatic rings are present, the ring may be fused, such as a naphthyl or an anthracenyl group. The aryl group may optionally be substituted, such as a halogen, nitro, cyano group, optionally substituted C ₁ -C ₁₅ straight chain, branched chain or cyclic alkyl group, such as a fluorinated or unfluorinated butyl group, Isobutyl, hexyl, decyl, cyclohexyl, adamantyl and norbornyl, alkenyl, alkynyl, C ₆ -C ₁₈ aryl, such as benzyl, phenyl, naphthyl or anthracyl, And their combinations. Ar ₁ contains no crosslinkable groups, including, for example, a hydroxyl group.

Preferably, the first unit of the formula (I) is a unit selected from the group consisting of (IA), (IB) and (1-C): Wherein: R _{1 is} selected from the group consisting of hydrogen, fluorine, C ₁ -C ₃ alkyl and C ₁ -C ₃ fluoroalkyl, wherein hydrogen is typically hydrogen; R _{2 is} independently selected from halogen, nitro, cyano and optionally substituted C ₁ -C ₁₅ straight chain, branched chain or cyclic alkyl group, such as fluorinated or unfluorinated butyl, isobutyl, hexyl, decyl, cyclohexyl, adamantyl and norbornyl, alkenyl , alkynyl, C ₆ -C ₁₈ aryl, such as benzyl, phenyl, naphthyl and anthracenyl, and combinations thereof, wherein hydrogen is typically, and R ₂ does not contain a crosslinkable group, such as a hydroxyl group; An integer from 0 to 5, typically 0 or 1; b is an integer from 0 to 7, typically 0 to 2, or 0 or 1; and c is an integer from 0 to 9, typically 0 to 3, or 0 or 1 . The first unit has surface energy, optical properties (such as n and k values) and/or glass transition temperatures for tuning the uncrosslinked crosslinkable polymer.

The applicable structure of the first unit includes the following:

Among these structures, styrene is preferred. The first unit is generally present in the uncrosslinkable crosslinkable polymer in an amount of from 30 to 99 mol%, preferably from 80 to 98 mol%, based on the polymer.

The crosslinkable polymer that has not been crosslinked includes the second unit of the following general formula (II): Wherein: R _{3 is} selected from the group consisting of hydrogen, fluorine, C ₁ -C ₃ alkyl and C ₁ -C ₃ fluoroalkyl; and R _{4 is} selected from C ₁ to C ₁₂ straight, branched or cyclic as desired. And an optionally substituted C ₆ to C ₁₅ aryl group (e.g., phenyl, naphthyl, anthracenyl), the aryl group optionally containing a hetero atom; and at least one of the hydrogen atoms in the group Substituted by a functional group independently selected from the group consisting of a hydroxyl group, a carboxyl group, a thiol, an amine, an epoxy group, an alkoxy group, a decylamine, and a vinyl group. Among them, a hydroxyl group is preferred. The functional groups at the R ₄ position are not limited, but may be located, for example, at the primary, secondary or tertiary position. In the case of hydroxyl groups, primary, secondary or tertiary alcohols can be used.

Suitable structures for the second unit include the following:

In the crosslinkable polymer, the second unit is typically present in an amount of from 1 to 70 mol%, such as from 1 to 50 mol%, from 1 to 20 mol%, or from 1 to 10 mol%, based on the polymer. If the content of the first unit relative to the second unit is too low, it is generally believed that the gap-filling ability for a small, high aspect ratio slit may be deteriorated. If it is too high, the resistance of the polymer against swelling and stripping may be deteriorated. It will deteriorate due to insufficient cross-linking.

In one aspect, the repeating unit of the uncrosslinked crosslinkable polymer comprises only units of the formula (I) and the formula (II), ie the polymer is only of the formula (I) and the formula The unit of (II). In this case, the uncrosslinked crosslinkable polymer can be made from a single type of unit of formula (I) and a unit of unit of formula (II) of a single type. Alternatively, the crosslinkable polymer may comprise different types of units of formula (I), and/or different types of units of formula (II).

In another aspect, the uncrosslinked crosslinkable polymer can include one or more additional units in addition to formulas (I) and (II). The polymer may, for example, include one or more additional units to adjust the properties of the interstitial composition, such as etch rate and solubility. Suitable additional units include, for example, one or more units selected from the group consisting of (meth) acrylate (for solubility), vinyl ether, vinyl ketone and vinyl ester (for faster etching), preferably There is no crosslinkable group in the side chain.

Appropriate additional units include the following:

If present in the crosslinkable crosslinkable polymer, the one or more additional units may be used in an amount of up to 69 mol%, preferably 5 to 50 mol%, based on the polymer.

Since the crosslinkable polymer is uncrosslinked in the composition, it can more efficiently fill gaps of small size and high aspect ratio, such as voids, grooves and interline spaces, and other features. This is generally believed to be the result of lower molecular weight and volume compared to crosslinked materials.

The uncrosslinked crosslinkable polymer preferably has a hydrophobic character similar to polystyrene. Without wishing to be bound by any particular theory, it is believed that the hydrophobic polymer is relatively inert to the interaction of the substrate surfaces. In contrast, hydrophilic groups such as hydroxyl groups and carboxyl groups are generally The surface of the substrate has a covalent or non-covalent effect. It is generally believed that the interaction of the hydrophilic group with the surface during the coating process hinders the interstitial effect of the composition. The degree of hydrophobicity can be determined by gradient polymer stripping chromatography (GPEC). According to GPEC analysis, the maximum peak lag time of the preferred interstitial composition of the present invention is within 90% of that of polystyrene.

The uncrosslinked crosslinkable polymer generally has a weight average molecular weight of greater than 6000, such as from 6,000 to 30,000, preferably greater than 8,000, greater than 9000, or greater than 10,000, greater than 8,000 to less than 20,000, 9000 to 18,000, typically 10,000 to 15,000. The preferred molecular weight allows for reasonable yields during synthesis, as well as low swelling/high solvent stripping resistance to solvents, where the intervening composition is in contact with the use of the interstitial composition, such as for use in a bottom anti-reflective coating. (BARC), solvent for photoresist and developing materials. High swelling/low stripping resistance can cause pattern collapse during the patterning of the upper photoresist.

The polydispersity index (PDI) of the crosslinkable polymer which is not crosslinked is not particularly limited. In general, the crosslinkable polymer has a polydispersity index (PDI) of 1.05 or higher, typically from 1.05 to 2.0.

Preferably, the glass transition temperature (T _g ) of the uncrosslinked crosslinkable polymer is 10 ° C or more, preferably less than the polymerization temperature (T _o ) of the crosslinking reaction of the polymer. The starting temperature of the cross-linking reaction is 15 ° C or more, 20 ° C or more, or 30 ° C or more. As described above, the glass transition temperature was measured by differential scanning calorimetry (DSC, increasing rate of 20 ° C / min). The temperature difference between this starting temperature and the glass transition temperature is defined by the following formula: △T _og =T _o -T _g.

By selecting a crosslinkable polymer having a sufficiently high ΔT _og , pre-crosslinking of the polymer can be prevented when the composition is heated, such as during soft baking as described below or as needed during the caulking process Heating. Further, the interstitial composition of the present invention contains an uncrosslinked crosslinkable polymer having a sufficiently high ΔT _og and generally having a very good planarization. The uncrosslinked crosslinkable polymer is typically present in the interstitial composition in an amount of from 60 to 95% by weight, such as from 85 to 95% by weight, or from 90 to 95% by weight, based on the total solids of the composition.

Suitable crosslinkable polymers useful in the present invention include the following:

The crosslinking agent useful in the present invention is one which is capable of undergoing acid-catalyzed crosslinking reaction with the crosslinkable polymer. Suitable crosslinking agents include, for example, di-, tri-, tetra- or higher poly-functional ethylenically unsaturated monomers. Crosslinking agents useful in the present invention include, for example, trivinylbenzene, divinyltoluene, divinylpyridine, divinylnaphthalene, divinylxylene, ethylene glycol diacrylate, trimethylolpropane three Acrylate, diethylene glycol divinyl ether, trivinylcyclohexane, allyl methacrylate ("ALMA"), ethylene glycol dimethacrylate ("EGDMA"), diethylene glycol II Methacrylate ("DEGDMA"), propylene glycol dimethacrylate, propylene glycol diacrylate, trimethylolpropane trimethacrylate ("TMPTMA"), divinylbenzene ("DVB"), methyl Glycidyl acrylate, 2,2-dimethylpropane 1,3 diacrylate, 1,3-butanediol diacrylate, 1,3-butanediol dimethacrylate, 1,4-butane Alcohol diacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, tripropylene glycol II Acrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, tetraethylene glycol dimethyl propylene Acid ester, polyethylene glycol dimethacrylate, ethoxylated bisphenol A diacrylate, ethoxylated bisphenol A dimethacrylate, polyethylene glycol dimethacrylate, poly (butyl) Diol) diacrylate, pentaerythritol triacrylate, trimethylolpropane triethoxy triacrylate, glyceryl propoxy triacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, dipentaerythritol monohydroxyl Pentaacrylate, divinyl decane, trivinyl decane, dimethyl divinyl decane, divinyl methyl decane, methyl trivinyl decane, diphenyl divinyl decane, divinyl phenyl decane , trivinylphenyl decane, divinylmethyl phenyl decane, tetravinyl decane, dimethyl vinyl dioxane, poly (methyl vinyl siloxane), poly (vinyl hydrazine) Alkanes, poly(phenylvinyloxiranes), tetra(C ₁ -C ₈ )alkoxyacetylene ureas such as tetramethoxyacetylene urea and tetrabutoxyacetylene urea, and combinations thereof. Preferably, the crosslinking agent is a tetraalkoxyalkylacetylene urea, hexamethylol melamine or an aromatic compound having a polyfunctional group suitable for carrying out an acid-catalyzed crosslinking reaction. Suitable crosslinkers are commercially available. The crosslinking agent is generally present in an amount of from 4 to 25 wt%, such as from 10 to 22 wt%, based on the total solids of the composition.

Acid catalysts useful in the present invention include free acids and acid generators. Any free acid which is compatible with the compositions of the present invention and which catalyzes the crosslinking reaction of the polymer with the crosslinking agent is suitable for use in the present invention. Examples of free acids include, but are not limited to, sulfonic acids such as methanesulfonic acid, ethanesulfonic acid, propylsulfonic acid, phenylsulfonic acid, toluenesulfonic acid, dodecylbenzenesulfonic acid, and trifluoromethanesulfonic acid. .

Suitable acid generators include thermal acid generators (TAG), photoacid generators (PAGs), and combinations thereof. The thermal acid generator is a compound which generates an acidic moiety upon heating. The thermal acid generator can be nonionic or ionic. Suitable nonionic thermal acid generators include, for example, p-toluenesulfonic acid cyclohexyl ester, p-toluenesulfonic acid methyl ester, 2,4,6-triisopropylbenzenesulfonate cyclohexyl ester, nitrobenzyl ester , benzoin tosylate, 2-nitrobenzyl tosylate, tris(2,3-dibromopropyl)-1,3,5-three -2,4,6-trione, alkyl sulfonate, organic sulfonic acid such as p-toluenesulfonic acid, dodecylbenzenesulfonic acid, oxalic acid, phthalic acid, phosphoric acid, camphorsulfonic acid, 2 , 4,6-trimethylbenzenesulfonic acid, triisopropylnaphthalenesulfonic acid, 5-nitro-o-toluenesulfonic acid, 5-sulfosalicylic acid, 2,5-dimethylbenzenesulfonic acid, 2-nitrobenzenesulfonic acid, 3-chlorobenzenesulfonic acid, 3-bromobenzenesulfonic acid, 2-fluorooctylnaphthalenesulfonic acid, dodecylbenzenesulfonic acid, 1-naphthol-5-sulfonic acid, 2 -Methoxy-4-hydroxy-5-benzylidene-benzenesulfonic acid and salts thereof, and combinations thereof. Suitable ionic thermal acid generators include, for example, triethylamine dodecylbenzenesulfonate, triethylamine dodecylbenzenedisulfonate, ammonium p-toluenesulfonate, sulfonate Classes such as carbocyclic aryl (eg, phenyl, naphthyl, anthracenyl, etc.) and heteroaryl (eg, thienyl) sulfonate, aliphatic sulfonate and besylate. Compounds which can produce sulfonic acids upon activation are generally suitable. Preferred thermal acid generators include ammonium p-toluenesulfonate.

The photoacid generator is a compound which, when exposed to activating radiation, produces an acidic moiety. Suitable photoacid generators include compounds such as sulfides and phosphonium salts. Photoacid generators include, but are not limited to, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroarsenate, diphenyliodonium hexafluoroantimonate, diphenyl-p-methoxyphenyl three Fluoromethanesulfonate, diphenyl-p-tolyltrifluoromethanesulfonate, diphenyl-p-isobutylphenyltrifluoromethanesulfonate, diphenyl-p-tert-butylphenyltrifluoromethane Sulfonate, triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroarsenate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium trifluoromethanesulfonate, (4-third Phenyl)tetramethylene sulfonium (3-hydroxyadamantyl ester)-tetrafluorobutane sulfonate), (4-t-butylphenyl)tetramethylene sulfonium (adamantyl ester)-four Fluorane sulfonate), and dibutylnaphthyl fluorene triflate. Preferred PAGs include tetramethylene sulfonium compounds.

Certain photoacid generators can also act as thermal acid generators which generate acid upon exposure to activating radiation or heat. For example, the following compounds can be used as PAG or TAG:

When used as TAG, these compounds provide relatively low cross-linking (high cross-linking initiation temperature) compared to ammonium salts, thus achieving high ΔT _og .

Combinations of acid catalysts can be used in the present invention. Suitable combinations include, for example, photoacid generators and free acids, thermal acid generators and free acids, or photoacid generators and thermal acid generators.

Suitable acid catalysts are commercially available. The acid catalyst is generally present in the composition in an amount of from 0.1 to 8 wt%, preferably from about 0.5 to about 5 wt%, based on the total solids of the composition.

The interstitial composition further includes a solvent, which may include a single solvent or a solvent mixture. The solvent material suitable for formulating and casting the interstitial composition has very good solubility characteristics for the non-solvent component of the interstitial composition, but does not significantly dissolve the underlying relief image or the surface of the substrate will be in contact with the interstitial composition Other materials. The solvent is generally selected from the group consisting of water, aqueous solutions, organic solvents, and mixtures thereof. The solvent is preferably an organic solvent. Suitable organic solvents for the interstitial composition include, for example, alcohols such as linear, branched chains or cyclic C ₄ -C ₉ monohydric alcohols such as 1-butanol, 2-butanol, isobutanol, and third. Alcohol, 2-methyl-1-butanol, 1-pentanol, 2-pentanol, 4-methyl-2-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 2-hexyl Alcohol, 2-heptanol, 2-octanol, 3-hexanol, 3-heptanol, 3-octanol, and 4-octanol; 2,2,3,3,4,4-hexafluoro-1- Butanol, 2,2,3,3,4,4,5,5-octafluoro-1-pentanol and 2,2,3,3,4,4,5,5,6,6-fluorene- 1-hexanol, with C ₅ -C ₉ fluorinated diol such as 2,2,3,3,4,4-hexafluoro-1,5-pentanediol, 2,2,3,3,4,4 ,5,5-octafluoro-1,6-hexanediol, and 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoro-1,8-octyl a glycol; an ester solvent such as an alkyl acetate such as n-butyl acetate, a propionate such as n-butyl propionate, n-pentyl propionate, n-hexyl propionate and n-heptyl propionate, and an alkyl butyrate. Base esters such as n-butyl butyrate, isobutyl butyrate and isobutyl isobutyrate, diethyl carbonate, methyl acetate, ethyl acetate, γ-butyrolactone, γ-valerolactone, ethylene glycol Monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, B Glycol monoethyl ether acetate, diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, Propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, diacetin, methoxy triglyceride, ethyl propionate, C N-butyl acrylate, isoamyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate, diethyl malonate, o-benzene Dimethyl dicarboxylate, diethyl phthalate, methyl 2-hydroxyisobutyrate and the like; ketones such as 2,5-dimethyl-4-hexanone and 2,6-dimethyl- 4-heptanone; aliphatic hydrocarbons such as n-heptane, n-decane, n-octane, n-decane, 2-methylheptane, 3-methylheptane, 3,3-dimethylhexane and 2 3,4-trimethylpentane, and a fluorinated aliphatic hydrocarbon such as perfluoroheptane; an ether such as isoamyl ether or dipropylene glycol monomethyl ether; and a mixture containing one or more of these solvents. Among these solvents, propylene glycol monomethyl ether acetate, γ-butyrolactone, methyl 2-hydroxyisobutyrate, and combinations thereof are preferred. The solvent component of the interstitial composition is generally present in an amount of from 80 to 99% by weight, more preferably from 90 to 99% by weight, or from 95 to 99% by weight, based on the total weight of the interstitial composition.

The interstitial composition can include one or more optional additives, including, for example, surfactants and antioxidants. The optional additives are generally present in the composition in minor amounts, such as from 0.01 to 10% by weight, based on the total solids of the interstitial composition.

Typical surfactants include those having amphiphilic properties, meaning that they are both hydrophilic and hydrophobic. The amphiphilic surfactant has a hydrophilic head group or group that has a strong affinity for water, as well as a long hydrophobic tail which is organophilic and repels water. Suitable surfactants can be ionic (ie anionic, cationic) or nonionic. Other examples of surfactants include polyoxyn surfactants, poly(alkylene oxide) surfactants, and fluorochemical surfactants. The suitable nonionic surfactants include, but are not limited to, octyl and nonyl phenol ethoxylates such as ^{TRITON TM X-114, X-} 100, X-45, X-15 and branched secondary alcohol chain B oxides, such as ^{TERGITOL TM TMN-6 (The Dow} Chemical Company, Midland, Michigan USA). Other exemplary surfactants include (primary and secondary) alcohol ethoxylates, amine ethoxylates, glucosides, reduced glucosamines, polyethylene glycols, poly(ethylene glycol-co-propylene glycol), or other to reveal by the manufacturer Confectioners Publishing Co.of Glen Rock, NJ publication McCutcheon's Emulsifiers and Detergents, 2000, North American edition of the surfactant. Nonionic surfactants of acetylenic diol derivatives are also suitable. This surfactant may be commercially available from Air Products and Chemicals, Inc.of Allentown, PA, under the tradename SURFYNOL ^TM and DYNOL ^TM. Additional applicable surfactants include other polymeric compounds such as tris - block copolymers EO-PO-EO ^{PLURONIC TM 25R2, L121, L123,} L31, L81, L101 and P123 (BASF, Inc.).

Antioxidants may be added to prevent or minimize oxidation of the organic material in the interstitial composition. Suitable antioxidants include, for example, phenolic antioxidants, antioxidants composed of organic acid derivatives, sulfur-containing antioxidants, phosphorus-based antioxidants, amine-based antioxidants, antioxidants composed of amine-aldehyde condensates, and amines. An antioxidant composed of a ketone condensate. Examples of the phenolic antioxidant include hydroxy-substituted phenols such as 1-oxy-3-methyl-4-isopropylbenzene, 2,6-di-t-butylphenol, 2,6-di-third Butyl-4-ethylphenol, 2,6-di-tert-butyl-4-methylphenol, 4-hydroxymethyl-2,6-di-t-butylphenol, butyl-hydroxybenzoate Ether, 2-(1-methylcyclohexyl)-4,6-dimethylphenol, 2,4-dimethyl-6-tert-butylphenol, 2-methyl-4,6-didecyl Phenol, 2,6-di-tert-butyl-α-dimethylamino-p-cresol, 6-(4-hydroxy-3,5-di-t-butyl-2-anilino)-2, 4-double ‧ octyl-thio--1,3,5-three , n-octadecyl-3-(4'-hydroxy-3',5'-di-t-butyl-2-phenyl)propionate, octylated phenol, aralkyl substituted phenol, alkane P-cresol, and hindered phenol; bis-, tri- and poly-phenols, such as 4,4'-dihydroxy‧ diphenyl, methylene bis (dimethyl-4,6-phenol) , 2,2'-methylene-bis-(4-methyl-6-tert-butylphenol), 2,2'-methylene-bis-(4-methyl-6-cyclohexyl phenol ), 2,2'-methylene-bis-(4-ethyl-6-tert-butylphenol), 4,4'-methylene-bis-(2,6-di-t-butyl Phenol), 2,2'-methylene-bis-(6-α-methyl-benzyl-p-cresol), methylene-crosslinked polyvalent alkyl phenol, 4,4'-butylene Bis-(3-methyl-6-tert-butylphenol), 1,1-bis-(4-hydroxyphenyl)-cyclohexane, 2,2'-dihydroxy-3,3'-di- (α-methylcyclohexyl)-5,5'-dimethyl‧diphenylmethane, alkylated bisphenol, hindered bisphenol, 1,3,5-trimethyl-2,4,6-three (3,5-di-t-butyl-4-hydroxybenzyl)benzene, tris-(2-methyl-4-hydroxy-5-t-butylphenyl)butane, and tetra-[sub- Base-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane. Antioxidant is applicable on commercially available Irganox ^TM freely antioxidant (Ciba Specialty Chemicals Corp.).

The interstitial composition can be prepared according to known procedures. For example, the composition can be prepared by dissolving a solid component in the composition in a solvent component. The total solids content desired in the composition depends on factors such as the desired final layer thickness. In general, the interstitial composition has a solid content of from 1 to 20% by weight, such as from 1 to 10% by weight, more preferably from 1 to 5% by weight, based on the total weight of the composition.

According to a first aspect, the method of the invention will be described in Figures 1A through 1D. FIG. 1A illustrates a cross-sectional view of the semiconductor substrate 2. The substrate may be, for example, a semiconductor such as a germanium or a semiconductor compound such as III-V or II-VI, glass, quartz, ceramic, copper, or the like. In general, the substrate is a semiconductor wafer, such as a single crystal germanium, and may have one or more layers and patterned features formed on its surface. The layer forming part of the substrate may comprise, for example, one or more layers of a conductor such as aluminum, copper, molybdenum, niobium, titanium, tungsten, an alloy or a nitride or telluride layer of these metals, doped amorphous or doped Polycrystalline germanium, one or more dielectric layers, such as a cerium oxide layer, a cerium nitride layer, cerium oxynitride or a metal oxide, a semiconductor layer such as a single crystal germanium, a carbon layer, and combinations thereof. The layers can be formed by various techniques such as chemical vapor deposition (CVD) such as plasma-enhanced CVD, low pressure CVD or epitaxial growth, physical vapor deposition (PVD) such as sputtering or vaporization, electroplating, or liquid coating techniques such as Spin coating.

The uppermost layer of the substrate comprises an embossed image 4 which defines the gap 6 to be filled. The gap to be filled may be present in the base substrate material itself, or in a layer on the base substrate material, and may be in various forms. The slit may be in the form of a groove or a hole, preferably as narrow as possible and high in height aspect ratio.

Embossed images are typically formed by a lithography process, such as photolithography or assembly processes such as directed assembly (DSA). Etching methods such as anisotropic dry etching are generally used to transfer the pattern to the underlying layer where the relief image and the gap are formed. The gap can be in the form of a hole, a groove or an interline space or other feature. In an exemplary embodiment, the slit extends completely through the layer of material from which the relief image is formed, exposing the underlying substrate. It may be desirable for the gap to extend only a portion of the material layer. In the photolithography method, it is preferred that the exposure wavelength be less than 300 nm, such as 248 nm, 193 nm or EUV wavelength (e.g., 13.4 or 13.5 nm), or exposed to an electron beam. The slit may be in the form of a groove or a hole having a height h and a width w , and may be a relatively narrow width and a relatively high height. The method and composition of the present invention are suitable for filling gaps having relatively high aspect ratios. As used herein, the aspect ratio (AR) is defined as AR = h / w , where h is the gap height and w is the slit width. In general, the slit width is from 1 nm to 200 nm, such as from 1 nm to 100 nm, from 1 nm to 50 nm, from 1 nm to 25 nm or from 1 to 10 nm, preferably less than 50 nm, such as less than 20 nm, less than 15 nm, less than 10 nm or less than 5 nm. The aspect ratio is generally from 1 to 20, such as from 2 to 20, or from 5 to 20.

As shown in Fig. 1B, the interstitial composition 8 described herein is applied to the relief image 4 of the wafer surface. The interstitial composition can be applied to the substrate by spin coating, dipping, roller coating or other general coating techniques. Among these methods, spin coating is typical and preferred. In the case of spin coating, the solids content of the interstitial composition can be adjusted to provide the desired film thickness, depending on the particular coating device utilized, solution viscosity Degree, coating tool speed and length of rotatable time. The desired coating thickness of the interstitial composition depends on the geometry of the gap to be filled. A typical interstitial composition 8 has a thickness of from about 200 to 3000 Å.

Thereafter, the interstitial composition is typically soft baked at a temperature and time at which the residual solvent can be evaporated from the layer. The soft bake temperature is below the start-up temperature to prevent immature cross-linking of the polymer. Soft baking can be carried out in a hot plate or oven, typically a heating plate. For example, soft baking can be performed on a hot plate that is also used to coat the wafer tracks of the interstitial composition. The soft bake temperature and time depend on the thickness of the particular composition and interstitial composition. Soft baking is generally carried out at a temperature of about 70 to 150 ° C for about 30 to 90 seconds.

Referring to Figure 1C, the composition is then heated at a temperature and time at which the crosslinkable polymer can be crosslinked, thereby forming a crosslinked polymer 8'. Cross-linking bake can be carried out in a hot plate or oven 14 that is also used to coat the interstitial composition, typically a heated plate. Soft baking can be performed on the hot plate of the wafer track. The cross-linking bake temperature and time depend on, for example, the thickness of the particular composition and the soft bake interstitial composition. The cross-linking baking is generally carried out at a temperature of about 150 to 300 ° C for about 30 seconds to 3 minutes. Cross-linking baking can be carried out by heating the interstitial composition at a single temperature or ramp temperature. The soft bake and cross-link bake can be carried out in a single process using the same heater, for example, by ramping the temperature from the soft bake temperature to the cross-linking temperature.

After the interstitial composition is crosslinked, further processing of the substrate is performed to form a final device, which may include a memory (such as a DRAM) or a logic device. The further processing includes, for example, on a substrate One or more layers 16 are formed, as shown in FIG. 1D, grinding, chemical-mechanical planarization (CMP), ion implantation, annealing, CVD, PVD, epitaxial growth, electroplating and etching techniques such as DSA and photolithography. Advantageously, the liquid layer containing the solvent can be applied directly onto the crosslinked interstitial composition by, for example, spin coating without intermixing with the underlying crosslinked material.

2A through 2F illustrate a method in accordance with another aspect of the present invention in which, as shown in Fig. 2B, the interstitial composition 8 applied to the wafer 2 does not completely fill the gap. This can occur in very fine gaps, high viscosity interstitial compositions, and/or high molecular weight crosslinkable polymers. Depending on the soft bake temperature, the interstitial composition and the gap size and geometry, partial or complete gap filling may occur during soft bake if the polymer viscosity is sufficiently reduced. Unless otherwise indicated, the above description of the process of Figure 1 can also be used to describe Figure 2.

When the gap filling is not complete after coating and soft baking, the soft baked interstitial composition may be at a temperature greater than the soft baking temperature and sufficient time for the interstitial composition to fill the plurality of gaps. Heating in the gap baking step. As shown in Figure 2C, the interstitial bake can be carried out by heating the plate or oven 12, wherein a heated plate is typically used. The interstitial baking can be performed on a hot plate such as a coating interstitial composition and a soft baked wafer track. The interstitial baking temperature and time depend on, for example, the thickness of the particular composition and the soft bake interstitial composition. The interstitial baking is generally carried out at a temperature of about 150 to 200 ° C for about 30 seconds to 10 minutes. Preferably, the interstitial baking temperature is 10 ° C or more below the starting temperature, preferably 20 ° C or more, or 30 ° C or more, below the starting temperature of the composition. Preferably, the interstitial baking The temperature is 15 ° C or more below the cross-linking baking temperature, preferably 25 ° C or more, or 35 ° C or more, below the cross-linking baking temperature. During the interstitial baking process, the viscosity of the soft bake interstitial composition 8 becomes lower, so that the material can fill the gap 6, as shown in Figures 2C and 2D.

Referring to Figure 2E, the composition is then heated at a temperature above the interstitial baking temperature to crosslink the uncrosslinked crosslinkable polymer. Cross-linking bake can be carried out in a hot plate or oven 14, typically a heated plate. Crosslinking bake can be carried out on a hot plate such as a wafer track that is also used to coat the interstitial composition. The cross-linking baking temperature depends on the thickness of the composition such as the specific composition and the soft bake interstitial. Cross-linking baking is generally carried out at a temperature of about 200 to 300 ° C for about 30 seconds to 30 minutes. Optionally, the interstitial baking and cross-linking baking can be carried out in a single process. For example, the interstitial and cross-linking bake can be performed sequentially, for example, using the same heating tool. The heating can be performed by, for example, varying the temperature of the continuous bevel or using a gradient temperature profile for the interstitial and cross-linking function. After the gap filling process, further processing can be performed to form the final device.

The following non-limiting examples are illustrative of the invention.

Example

Example 1: Synthesis of poly(styrene-co-HEMA)

The polymer feed solution is in a 100 ml glass vial, combining 48.14 g benzene An ethylene monomer (liquid) was prepared with 1.86 g of 2-hydroxyethyl methacrylate monomer (liquid). The bottle was gently shaken to mix the monomers and placed in an ice bath to bring the temperature of the monomer mixture to equilibrium with the ice bath. 1.373 g of a V601 azo starter (white powder, WakoPure Chemical Industries, Ltd.) was added to the bottle, and the bottle was shaken until the starter was completely dissolved. The bottle was again placed in an ice bath. 50 g of 1-butanol was poured into a three-necked 250 ml round bottom bottle equipped with a heat controller, which was flushed with nitrogen. A three-necked 250 ml round bottom flask containing the reaction mixture was heated to a temperature of 80 ° C to the reaction mixture. The monomer feed solution was fed to the reactor at a rate of 0.92 ml/min with a total feed time of about 60 minutes. After the monomer feed was complete, the reactor was maintained at 80 ° C for an additional hour. The heating was stopped and the reactor was cooled to room temperature and stirred. The resulting polymer solution was precipitated with methanol (10-fold excess of the reaction mixture), filtered and dried in vacuo.

Example 2: Synthesis of poly(styrene-co-HDMA)

The polymer feed solution was prepared in a 100 ml glass vial in combination with 39.79 g of styrene monomer (liquid) and 10.21 g of 2-hydroxynonyl methacrylate monomer (liquid). Gently shake the bottle to mix the monomers and place in an ice bath. The temperature of the monomer mixture is brought to equilibrium with the ice bath. 1.957 g of V601 azo starter (white powder, Wako Pure Chemical Industries, Ltd.) was added to the bottle, and the bottle was shaken until the starter was completely dissolved. The bottle was again placed in an ice bath. 50 g of 1-butanol was poured into a three-necked 250 ml round bottom bottle equipped with a heat controller, which was flushed with nitrogen. A three-neck 250 ml round bottom flask containing the reaction mixture was heated to a reaction temperature of 80 °C. The monomer feed solution was fed to the reactor at a rate of 0.83 ml/min with a total feed time of about 60 minutes. The reactor was maintained at 80 ° C for an additional hour after the monomer feed was complete. The heating was stopped and the reactor was cooled to room temperature and stirred. The resulting polymer solution was precipitated with methanol (10-fold excess of the reaction mixture), filtered and dried in vacuo.

Example 3: Interstitial composition 1

1.07 g of tetramethoxymethyl glycoluril, 0.057 g of p-TSA ammonium salt (T-1), 0.0036 g of fluorochemical surfactant, and 108.8 g of propylene glycol monomethyl ether acetate (PGMEA) 60 g of a PGMEA solution containing 10% by weight of the PS-HEMA polymer of Example 1 was added to obtain a 4.2 wt% solution based on the total weight of the composition. The solution was filtered through a 0.45 micron pore size PTFE microfilter to obtain interstitial composition 1.

Example 4: Interstitial composition 2

1.07g of tetramethoxymethyl glycoluril, 0.057g of p-TSA ammonium salt (T-1), 0.0036g of fluorochemical surfactant, and 108.8g of propylene glycol monomethyl ether acetate (PGMEA) were added to 60g. 10 wt% of the PGMEA solution of the PS-HDMA polymer of Example 2 was obtained as a 4.2 wt% solution based on the total weight of the composition. The solution was filtered through a 0.45 micron pore size PTFE microfilter to obtain interstitial composition 2.

Example 5: Interstitial composition 3

Add 1.07g of tetramethoxymethyl glycoluril, 0.07g of tetramethylenesulfonium salt (T-2), 0.0036g of fluorochemical surfactant, and 108.8g of propylene glycol monomethyl ether acetate (PGMEA) to 60g The PGMEA solution containing 10% by weight of the PS-HEMA polymer of Example 1 was used to obtain a 4.2 wt% solution based on the total weight of the composition. The solution was filtered through a PTFE microfilter having a pore size of 0.45 μm to obtain an interstitial composition 3.

Example 6: Solvent stripping test

The thermal crosslinking reaction of the crosslinkable polymer is monitored not directly by the solvent stripping test. Each of the interstitial compositions of Examples 3 to 5 was spin-coated on each bare Si wafer at 1500 rpm. The coated wafer was baked under a nitrogen atmosphere (O ₂ amount less than 100 ppm) and baked at several temperatures for 1 minute to obtain an initial coating thickness of 130 nm (t _i ). The film was thoroughly rinsed with a 1:1 PGMEA: HBM (2-hydroxymethyl methacrylate) solvent mixture to remove the uncrosslinked portion of the composition. The thickness (t _f ) of the insoluble crosslinked composition remaining on the substrate was measured, and the thickness loss was determined by (t _i -t _f )/(t _i ). The results are shown in Table 1.

The interstitial compositions 3 and 4 initially exhibited low thickness loss at 120 to 130 ° C, and the interstitial composition 5 began to exhibit low thickness loss at 205 ° C. These temperatures indicate the crosslinking initiation temperature of each polymer, and the low thickness loss indicates complete or near complete crosslinking.

Example 7: Interstitial process

A 8 inch patterned 400 nm LPCVD SiO ₂ system is provided on the wafer. The pattern includes a trench with 300 nm lines and spaces, and a trench with 150 nm lines and spaces. The interstitial composition of Example 3 was spin coated onto the wafer surface at 1500 rpm to provide a film thickness of about 100 nm. The composition was heated on a hot plate at 215 ° C for 1 minute to crosslink the polymer. The cross-linked trench pattern is shown in Figure 3A (300 nm 1:1 trench pattern with an aspect ratio of 1.33) and Figure 3B (150 nm 1:1 trench pattern with an aspect ratio of 2.0). The trench was filled and no holes were formed.

Example 8: Interstitial composition

The interstitial composition was prepared by combining the components and amounts shown in Table 2. The solution was filtered through a 0.45 micron pore size PTFE microfilter to obtain a gap filler composition.

Example 9: Interstitial process

An 8-inch wafer with a 535 nm thick LPCVD SiO ₂ pattern is provided. The pattern includes a trench having a width of 58 nm at the top of the trench, a width of 20 nm at the bottom of the trench, and a width of 45 nm in the middle of the trench (1/2). The interstitial compositions 2, 5, 9 and 13 were spin coated onto the patterned surface of each wafer at 1500 rpm to provide a film having a thickness of about 200 nm. The composition was heated on a hot plate at 215 ° C for 1 minute to cause cross-linking of the polymer. It was visually observed that the grooves were filled without void formation, such as FIG. 4A (composition 2), 4B (composition 5), 4C (composition 9), and 4D (composition 13). ) shown.

Example 10: Interstitial process

The procedure as described in Example 9 was repeated using the interstitial compositions 1, 3, 4, 6 to 8, 10 to 12 and 14 to 18. It is expected that the grooves can be visually observed to be filled without voids.

2‧‧‧Semiconductor substrate

4‧‧‧Relief imagery

6‧‧‧ gap

8‧‧‧Interstitial composition

8'‧‧‧crosslinked polymer

14‧‧‧heating plate or oven

16 ‧ ‧ layer

h ‧‧‧height

w ‧‧‧Width

Claims (12)

A gap filling method comprising: (a) providing a semiconductor substrate having a relief image on a surface, the relief image comprising a plurality of slits to be filled; (b) applying a gap filler composition to the relief image, wherein the gap filling composition The composition comprises an uncrosslinked crosslinkable polymer, an acid catalyst, a crosslinking agent, and a solvent, wherein the crosslinkable polymer comprises a first unit having the following general formula (I) and having the following general formula (II) The second unit: Wherein: R _{1 is} selected from the group consisting of hydrogen, fluorine, C ₁ -C ₃ alkyl and C ₁ -C ₃ fluoroalkyl; and Ar ₁ is an optionally substituted aryl group which does not contain a crosslinkable group; Wherein: R _{3 is} selected from the group consisting of hydrogen, fluorine, C ₁ -C ₃ alkyl and C ₁ -C ₃ fluoroalkyl; and R _{4 is} selected from C ₁ to C ₁₂ straight, branched or cyclic as desired. And a C ₆ to C ₁₅ aryl group optionally substituted with a hetero atom, wherein at least one hydrogen atom is substituted with a functional group independently selected from a hydroxyl group, a carboxyl group, a thiol, an amine And a guanamine, and a vinyl group; and (c) heating the interstitial composition at a temperature at which the polymer is crosslinked. The method of claim 1, wherein the first unit is selected from one or more of the following formulas (IA), (IB) and (1-C): Wherein R _{1 is} selected from the group consisting of hydrogen, fluorine, C ₁ -C ₃ alkyl and C ₁ -C ₃ fluoroalkyl; R _{2 is} independently selected from halogen, nitro, cyano, and optionally substituted C ₁ - C ₁₅ straight chain, branched chain or cyclic alkyl, alkenyl, alkynyl, C ₆ -C ₁₈ aryl, and combinations thereof, and R ₂ does not contain a crosslinkable group; a is an integer from 0 to 5 ;b is an integer from 0 to 7; and c is an integer from 0 to 9. The method of claim 2, wherein the first unit is: The method of any one of claims 1 to 3, wherein the second unit is selected from one or more of the following units: The method of claim 4, wherein the second unit is; The method of any one of claims 1 to 3, wherein the crosslinkable polymer consists of the unit of the formula (I) and the formula (II). The method of any one of claims 1 to 3, wherein The crosslinkable polymer has a weight average molecular weight of from 9000 to 20,000. The method of any one of claims 1 to 3, wherein the slit has a width of from 1 to 50 nm and an aspect ratio of from 2 to 20. The method of any one of claims 1 to 3, further comprising heating the interstitial at a temperature at which the interstitial composition fills the plurality of slits before crosslinking the interstitial composition Composition. The method of claim 9, wherein the heating of the plurality of slits and the heating for crosslinking are carried out in a single process. The method of any one of claims 1 to 3, wherein R _{4 is} selected from the group consisting of a C ₁ to C ₁₂ straight chain, a branched chain, a cyclic alkyl group, and a C ₆ to C ₁₅ aryl group, wherein At least one hydrogen atom is substituted with a hydroxyl group. A gap filling method comprising: (a) providing a semiconductor substrate having a relief image on a surface, the relief image comprising a plurality of slits to be filled; (b) applying a gap filler composition to the relief image, wherein the gap filling composition The composition comprises an uncrosslinked crosslinkable polymer, an acid catalyst, a crosslinking agent, and a solvent, wherein the crosslinkable polymer comprises a first unit having the following general formula (I) and a second unit: Wherein: R _{1 is} selected from the group consisting of hydrogen, fluorine, C ₁ -C ₃ alkyl and C ₁ -C ₃ fluoroalkyl; and Ar ₁ is an optionally substituted aryl group which does not contain a crosslinkable group; The two unit is selected from: or And (c) heating the interstitial composition at a temperature at which the polymer is crosslinked.